What is a Rim Joist?


Rim Joists, also referred to as “Headers” or “Belts” are a very critical area to focus on in regards to proper insulation. This space is located between the top of the basement wall, and the start of the first floor. For many homes, the rim joist is an un-insulated area that acts as a major source of heat loss and infiltration.

The Benefits of Insulating Rim Joists

What are the benefits of insulating rim joists with spray foam?

  • Lower utility costs
  • Save energy and preserve resources
  • Reduce moisture and mould
  • Stop bugs and pests from entering your living space

Lower Utility Costs and Energy Savings

If you’re like most homeowners, you are always looking for ways to save money on expenses while still maintaining a certain level of comfort. Unfortunately it can be challenging to keep expenses to a minimum if your home has insufficient insulation. Whether your house is old or brand new, if insulation is lacking or has been installed improperly, you will experience substantial drafts.

When your home isn’t sealed efficiently, your air-conditioner and heater have to work harder to maintain a comfortable temperature, costing you more money in the long-run. Adding additional standard insulation to this area won’t be effective in stopping air loss.

Insulating your rim joists with spray foam however, will help seal air from entering and exiting your home, keeping temperatures comfortable for your family and most importantly costs down!

Reduces Moisture and Mold

Your home’s air quality can be affected dramatically if the rim joist area contains a high level of moisture. Because roughly three quarters of your air infiltration comes from the basement, it’s crucial rim joists are insulated properly. Remember that a house breathes from the basement up, so if there is any moisture present this will increase the chances of mould growth and rot in this region. Your entire home will become infected by poor air quality if this occurs, posing potential health concerns.

Rim joists are above grade, so it’s important to insulate the joists to the same level as above-grade walls. At the rim joist region, many building components come together—the foundation wall, the mudsill, the rim joist, and the subfloor, so it’s crucial to properly seal all cracks from air leakage. Insulation Foam is ideal for rim joist insulation as unlike fiberglass batts, foam will prevent warm and humid air from entering the rim joists, thus eliminating mould growth.

Stops Pests

Spiders, bugs, and sometimes mice make their way through your home at the rim joist area in your basement. The wooden rim or band joist area is where the house’s wooden structure rests on the concrete foundation, and often there are gaps and cracks present here.

Why Eco Insulation for Your Rim Joists?

Unlike conventional fiber insulations, Eco Insulation is spray applied in a liquid format and expands into foam. It fills every single nook, cranny, crevice, hole, crack, and gap making a perfect continuous air-tight seal every time, regardless of complex framing and penetrations.

Eco Insulation Foam plugs gaps in your rim joists, creating a continuous air barrier seal so it won’t settle or sag, preventing air leakage. Many households will notice up to 50% savings on their utility bills!